Mesenchymal stromal cells (MSC): MSC are multipotent adult cells capable of differentiating down multiple mesenchymal lineages. They are adherent fibroblastoid-like cells with an extensive capacity for expansion. They reside within the connective tissue of most organs and have been isolated from bone marrow, placenta, adipose tissue, umbilical cord, amniotic fluid, circulating blood, various foetal tissues, skeletal muscle synovia, dental pulp, liver, spleen, lung and dermis. Most work has focussed on MSC derived from bone marrow, however, there are also some clinical reports using adipose tissue and placental derived MSC. MSC from different sources may not be functionally equivalent or exhibit the same differentiation potential. The main functions for bone marrow derived MSC with regards to the present study is the ability to differentiate down the osteogenic lineage. It is this ability to differentiate that has seen them applied to bony non-union and the treatment of critical size bone skeletal deficits, and in particular the reconstruction of cranial voids. In the current proposal Cell and Tissue Therapies W.A. at Royal Perth Hospital have extensive experience and have applied for an TGA (Therapeutics Goods Administration, the Australian Government regulatory authority) licence to manufacture and provide MSC for patient treatment.